JIT coverage can be improved considerably

JIT coverage is still quite variable. For some benchmarks, e.g. richards it is close to 100%.
For others, much lower:

https://github.com/savannahostrowski/pyperf_bench/blob/main/profiling/jit.svg

Note: A fair bit of the time attributed to the interpreter is frame cleanup, so makes the interpreter fractions look larger than they are.

We can increase JIT coverage, by:

• Treating dynamic exits, like side exits: warming up and compiling a new side trace.
• Adding possible jit entry points at function entries, as well as backward edges.

Linked PRs

• gh-143391
• gh-143977